Miniaturization of a design rule of semiconductor devices advances every year in accordance with high-degree integration and an increase in the speed of integrated circuits, such as ULSI circuits used for computers. Consequently, smaller defects on a semiconductor substrate have an adverse effect on the performance of the semiconductor device. At present, the control of nano-scale defects, which have not been conventionally problematic, is required.
A surface defect inspection device is used for the control of defects on a semiconductor substrate surface. Defects detected by a surface defect inspection device include foreign matter and residues on the semiconductor substrate. The foreign matter and the residues cannot be completely removed by a polishing process, a rinsing process, and a washing process. A common surface defect inspection device irradiates the surface of a semiconductor substrate with light, such as a laser beam, and receives and analyzes the reflected light as a signal to detect the existence and size of the defects.
When a polished, mirror-finished semiconductor substrate surface is irradiated with intense light, tarnish may be seen by diffused reflection caused by the roughness of the semiconductor substrate surface. The tarnish is referred to as haze. The haze can be used as the scale of the coarseness of a semiconductor substrate surface. When haze exists on a semiconductor substrate surface, diffused reflection light generated by the haze causes noise, which may hinder defect detection performed by a surface defect inspection device. Therefore, as the size of the defects to be detected, that the size of the defects to be controlled is smaller, the necessity of improving the haze level is increasing. It is known that the haze level of a semiconductor substrate surface is also strongly influenced by etching.
On the other hand, a surface treatment composition used to polish or etch a substrate generally contains a basic compound for etching the substrate surface. A surface treatment composition used to rinse or wash a substrate may also contain a basic compound for enhancing a rinsing or washing effect. However, when the pH of the surface treatment composition is set to 8 or more by blending a basic compound, roughness is disadvantageously apt to be generated on a substrate surface by the etching action caused by the basic compound. Therefore, when a substrate is subjected to surface treatment using a composition containing a basic compound and having a pH of 8 or more, reduction in the haze of the surface of the substrate that has been subjected to the surface treatment is required by controlling the etching action caused by the basic compound.
Patent Document 1 discloses a polishing composition containing a surfactant of a copolymer of polyoxyethylene and polyoxypropylene in order to mainly reduce the haze on a semiconductor substrate surface after polishing. However, the haze reduction effect caused by the polishing composition described in Patent Document 1 is not enough to control nano-scale defects.